The mixed-acid method is generally used in the production of isooctyl nitrate traditionally, i.e., at room temperature or low temperature condition, isooctyl alcohol is added dropwise to the mixture of acid consist of nitric acid and sulfuric acid. To maintain the low temperature of reaction system, the refrigerating brine is used to remove the heat generated by the esterification reaction. After the reaction finished, the product is poured into cold water for stratification, then the layer of ester is washed. Throughout the process, in order to prevent the side reactions of branched oxidation and nitrosation, all the operations must be carried out at low temperature, and a refrigerating machine must be needed to keep a steady low-temperature operation continuously. The investment of these devices and their ancillary equipments is large and energy consumption is also high. U.S. Pat. No. 2,768,964 (1956) provided a method for producing water and ester by azeotropical distillation under reduced pressure, through which nitrate of low boiling point was obtained with higher yield, but, the yield was only about 50% for nitrate of high boiling point; U.S. Pat. No. 4,479,905 (1984) provided a method for nitrifying the mixture of ethoxyethanol and isooctanol continuously. Thereof, at low temperature, the mixed acid ratio of water:nitric acid:sulfuric acid equaled to 12:20:68; Chinese Patent CN1031525A (1989) presented that at below 40° C. (optimum conditions: below 25° C. the mixed acid ratio of water:nitric acid:sulfuric acid equaled to 7-13:20-25:62-68, and the yield was 95-97%; Chinese patent ZL90105260.4 provided a method that at the temperature of 50-75° C., the mixed acid ratio of water:nitric acid:sulfuric acid equaled to 22-30:13-48:28-61, urea with 1-6% by weight of the mixed acid was added as stabilizer, blankets or other lipophilic hydrophobic materials were used for physical dehydration.
As to above technologies, some need cold source produced by refrigeration devices to keep reaction conditions at a low temperature, and the reaction is intermittent reaction. Because the reaction is exothermic process, the heat should be removed continuously to maintain the low temperature conditions of the system; when failure leads to disruption of refrigerant supply, the rising reaction temperature of the system promotes side reaction, consequently, the side reaction will release more heat so that the temperature of the system will rise rapidly, and eventually side reactions and oxidation reaction become main reactions. At this time, not only materials are lost largely, but also accidents such as material spraying or explosion are prone to occur, which endanger the safety of personnel and equipments, and will pollute the environment. The disadvantages of azeotropic distillation are high energy consumption and the problems of fundamental guarantee production safety. Although Chinese Patent ZL90105260.4 used overflow series reactor, but the equipments and processes were complex, the operation was difficult, more materials were stored in the system and there were still a lot of security risks.
In addition, the Chinese patent CN101698646A and CN101462962A also provided the process of producing isooctyl nitrate, which used a micro-tube (channel) reactor, but it was still unable to separate products in a timely manner. And because the channels of micro-tube (channel) reactor were much thin, which could easily be clogged by solid impurities from raw materials then the process was forced to shut down, so there were some limitations for the micro-tube (channel) reactor.
According to all of the above technologies, there exists a common security risk that the reaction product (ester) and the waste acid formed after the reaction can not be separated timely. The product may be further oxidized, which not only affects the quality and safety of the product, but also threats seriously to the safety of equipments and personnel.